


Firsts

by gwendee



Category: Assassination Classroom
Genre: Canon Compliant, F/M, Family Dynamics, I made Gakuhou an Awkward Teenager, Mamasano, Pre-Canon, i think
Language: English
Status: Completed
Published: 2019-10-25
Updated: 2019-12-11
Packaged: 2021-01-03 03:49:54
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 1,841
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/21172946
Author URL: https://archiveofourown.org/users/gwendee/pseuds/gwendee
Summary: Gakuhou's a practical man. When he set out in life he'd pledged to do three things: earn money, finish his masters, and set up a school, not necessarily in that order. Shiina had crashed into his life and Gakuhou found her fitting into the gaps of his plans like she'd belonged there.Gakushuu was part of that plan. He'd ruminated over it, researched it, and when she told him she was finally pregnant he'd panicked and got his bachelors in early childhood education.Written for handy-dandy-headcanons's rarepair week on tumblr!





	1. Chapter 1

**Author's Note:**

> Hey guys, it's me again, back with Day 2 of handy-dandy-headcanon's rarepair week on [tumblr](https://handy-dandy-headcanons.tumblr.com/post/187052555016/rules-the-banned-ships-are-given-due-to-how). Day 2: First. 
> 
> This is... kind of weird, I think, but I like it anyhow. I need more Mamasano.

**Firsts**  


It was fascinating, really, how she handled Gakushuu with such an ease he never could, bouncing him on her hip and playing around with him just came naturally to her in a way that Gakuhou can't comprehend.

"You," she says, poking him on the nose, "think too much."

Gakuhou's a practical man. When he set out in life with his diploma and his resolve he'd pledged to do three things: earn money, finish his masters, and set up a school, not necessarily in that order. Shiina had crashed into his life and she hadn't messed up his plans, no, because life has a funny way of working out and Gakuhou found her fitting into the gaps of his concepts and mindmaps like she'd belonged there.

Gakushuu was part of that plan. He'd ruminated over it, researched it, and when she told him she was finally pregnant he'd panicked and got his bachelors in early childhood education.

But now here he was, Gakushuu, a year old, bumbling around the world with an enviable curiosity and absolutely genuinely perplexing. Degrees, Gakuhou decides, were useless in practicality. His school would need to change that. 

Gakuhou watches him bat at a hanging mobile, full of shiny cutouts and fluffy pom-poms and bells. "Children are attracted to changes in environmental stimuli," he says, and Shiina rolls her eyes at him.

"Babies," she says, "like touching things. Like their papa."

"They're information gathering. I shouldn't restrict-"

"Gakuhou, hold your baby."

Baby Gakushuu graces him with the world's most unimpressed look. Gakuhou realizes with incredible dismay that this expression comes from him. 

"He looks just like you," Shiina says, sighing as she leans into him, Gakushuu pressed between them babbling at the television. "I'm so glad you're the pretty one out of the both of us."

"No, I'm not," Gakuhou says, tugging her closer. She pats his cheek.

He really isn't. Gakuhou knows he's attractive, in an objective sense, and in a subjective sense because, well, he is. Shiina had messy hair and tired eyes and had run smack into him (a rather literal crash, her books went flying as did his coffee but he didn't quite mind), and then yelled at him for staining her shirt whilst in two differently colored sandals and a scrunchie half-falling out of her hair.

He'd been smitten from that first day on.

He'd been in his third year of his first degree in business and she was on her second year in her first. "Biomedical engineering," she sighs into her (new) coffee. "Who says 'first degree'? Are you a weirdo? How many are you planning to have?" 

Gakuhou blinks. "Five."

She splutters, coughs, dabs her lips with a piece of tissue. "Are you a genius? Are you insane?  _ Are you insane _ ?" 

"No," Gakuhou says, "I have a ten year plan. Do you want to hear it?"

Shiina looks at him. "This is the weirdest fucking first date I've ever been on." She downs the rest of her coffee like a shot, stretches, then says, "yes."

She ends up part of his twenty year plan, (and eventually his 50-year plan, in all honesty he hasn’t thought that far yet but he knows he wants her to be a part of it). She rolls her eyes and tells him not to fool around too much in Harvard as he vehemently promises he wouldn't, and then kisses him in the airport like a hollywood cliche. When he comes back to Japan, he has seven years worth of letters he wrote her, and a ring.

Shiina agrees to be his first wife, on account that he doesn't think about getting a second. 

"You have to drop that," Gakuhou says.

"You introduced me as your first girlfriend!" She says. 

"I'm sorry!" Gakuhou says, pulling her close. "You know I'm-"

"Obsessed with numbers."

"-inexperienced," he interrupts petulantly, which is something he has trouble admitting. He doesn't like to be less than perfect at anything. She laughs at him the first time he brings it up and says, "then why are you in college, weirdo?"

Shiina smiles at him.

"Romantic entanglements are- were, unnecessary, in my plans."

"I just can't  _ wait _ to hear your vows," she deadpans, and then does an unflattering baritone of his voice. "Oh babe, I'm so happy to be your first husband-"

"Who's the second?" He demands.

"Your alternate personality," she says, and kisses him.

(She reminds him of this much later, when he's quietly crying in their bedroom. "My first husband got his heart broken," she says, "so I guess I'm sticking with you.”)

They have one wedding, one reception, one honeymoon (although they wouldn’t quite have minded if they had two). Shiina says, “I want a baby,” and Gakuhou splutters in his coffee. 

“How many?!”

She graces him with the world’s flattest look. “Let’s start with one.”

Gakuhou has his first son (his only son, thus far) at age 27. He has six degrees by then, two masters, and none of them have ever prepared him for this. 

"Honestly," she says, cutting him off mid deliberation about the optimal handling techniques as the nurse giggled at him. "Just hold your son."

Gakushuu was  _ tiny _ . His body almost fit into his entire palm, his head was soft and squishy, and his face was red and scrunched up.

"It's a baby," Gakuhou says in awe.

"No shit," Shiina says, closing her eyes. "Don't break him in half. I spent nine months making that."

"Oh," Gakuhou says.

**Notes for the Chapter:**

> Spoiler alerts: he does


	2. Chapter 2

**Notes for the Chapter:**

> Just a little add-on because my mind keeps turning. It breaks the flow of the first chapter so I was a little reluctant to post it, but I guess they can be read separately...? And since I already wrote it, I figured I'd just post it.

“I fucked up.”

“Mhm,” Shiina says, groggy, but she still rolls over to stare at his face. “How do you feel about it?”

“Bad,” Gakuhou admits. 

“He’s going to be angrier when he finds out,” she says. “You can’t keep it under wraps forever.”

“I just,” Gakuhou says, curling his fists under the blankets, “I wanted to protect-”

“I know,” she interrupts. “I’m not the person you have to explain that too.”

Gakuhou sighs. She cuddles up to him, closes her eyes, and says, “prepare yourself for a few miserable months. That boy inherited your bitterness.”

Gakuhou swallows. “Will you-”

“Nope,” she says. “It’s your turn to do damage control. Mama’s going to sit in the backseat this time.” She peeks an eye open to stare judgmentally from his chest. “Is Papa going to take defeat gracefully like my first husband or is he going to whine about being bested at the game by his fifteen year old son?”

“He didn’t best me,” Gakuhou tries fruitlessly.

“He toppled your entire education regime that you chose to raise him under,” Shiina says peacefully. “I’m so proud.”

Gakuhou frowns, and pulls her closer. "Shiina…"

"Gakuhou," she parrots. "You boys are hopeless."

Gakuhou sighs. 

“You’re going to apologize to him,” Shiina says.

“Of course I am,” Gakuhou says. “Just…”

“Can you just say ‘I’m sorry’ like a normal person for once?” Shiina says. “No calculations, no debate. Just go up and give him a hug.”

There’s a pause between them, as they attempt to picture the scene. “Maybe not a hug,” Shiina acqueises, “I like both of you in one piece.” 

The next morning, she ruffles their son’s hair and gives Gakushuu a peck on the cheek, and he smiles at her in such a soft and sad way Gakuhou had never registered before. Gakushuu is almost out the door when Gakuhou calls his name, and he stops and stares at him with a tiredly triumphant expression. “What?”

“I,” Gakuhou starts, and swallows.

Gakushuu blinks at him with wide eyes, and his bewildered gaze flicks to Shiina.

They stare at each other for several agonizing minutes. The clock ticks with each passing second, Shiina still has her knife poised to cut into her pancakes and Gakushuu is mid-step over the threshold. The silent staredown continues. 

Gakuhou admits defeat. “Just go.”

Gakushuu seems delighted to be dismissed from the horrifying awkwardness. He bolts. 

Shiina crosses her arms and shakes her head. “Try again, honey.”

“Children are perplexing,” Gakuhou tells her miserably.

“You’re a school principal!” She smacks him. 

“You were never a normal person, were you,” Gakushuu blurts, partway through dinner that night, and Gakuhou almost chokes on his food. He forces himself to take a deep breath, exchanges a wide-eyed look with his wife, then stares at his son, who’s staring back with what seems to be a new appraisal in his eyes. 

“Pardon?” Gakuhou says. 

“I had always been under the impression that you used to be a normal human being before Ikeda died,” Gakushuu says, “but you’ve always just been a weirdo, haven’t you?” He turns to Shiina, “Hasn’t he, mom.”

Shiina, who had thus far done a poor job of concealing her amusement, sprays food across the table. She dissolves into incomprehensible giggles, Gakushuu looks on in glee, and Gakuhou regrets everything in his life that has brought him to his moment. 

“H-h-he,” Shiina says, jabbing a finger in Gakuhou’s chest across the table. “Your father went back to college and got a bachelor’s degree in early childhood education the week I told him I was pregnant with you!”

“Much good that did!” Gakushuu exclaims.

“He tried to teach you trigonometry,” Shiina gasps for air, “you were three. You didn’t even know what triangles are!”

“Children start recognizing shapes when they’re two,” Gakuhou says weakly. 

“Don’t think your papa is all 'suave' and 'cool',” Shiina says, making exaggerated finger quotes, “he’s absolutely useless!”

“Shiina!” Gakuhou says in dismay.

“Oh, I know,” Gakushuu says. His flesh and blood, his little clone, the splitting image of him with a terrifying grin on his face. “You were trying to apologize this morning, weren’t you?”

This time, Gakuhou does choke on his food.

"Come on, let's hear it," Gakushuu says. He sets his chopsticks down and leans forward, matching Shiina's grin. Gakuhou's only weaknesses.

Gakuhou looks between his still-giggling wife and his obnoxious son, and then says, “I’m sorry.” it comes out quieter and more serious than he expected, and his son’s mouth parts in a little soft whine that breaks his heart and heals it at the same time.  "I love you." 

Gakushuu sets his cutlery down and dashes up the stairs, and Gakuhou hears his door slam shut. When he turns to Shiina, she's smiling softly at him.

"You'll take forever to earn his forgiveness," she sighs. 

"I said I wouldn't," Gakuhou says, "I said I wouldn't break our first kid."

"Only kid," Shiina corrects. "I'm not young anymore, stop saying first like you want a second."

Gakuhou laughs a little sadly into her neck. "I broke him."

"You didn't break him," Shiina says. "Bruised him a little, definitely. He still loves you."

Gakuhou is quiet. He thinks about his family, his plans, his career, and the end of the world. "After all of this," he says, "if the world doesn't end, we'll take a vacation. Three of us." 

There’s a quiet as Shiina deliberates, and then she says, “the world would  _ really _ end if we put the both of you on an inescapable environment together. I'd like that.”

**Notes for the Chapter:**

> I've always wanted to figure out how the FUCK Mamasano (given that she's canonically alive) handles both her boys


End file.
